The invention provides a frequency-spectrum-similarity-evaluation-based single-end travelling wave fault location reflected wave identification algorithm. According to a high-frequency characteristic of a travelling wave, a proper traveling wave characteristic time window is cut out to form a wave head spectrum similar function with full consideration of the high-frequency distribution characteristic; a fault transient travelling wave is analyzed by using a frequency spectrum analysis method; and the working efficiency and the accuracy of wave head identification are improved by using a similar spectrum optimization method. With the algorithm, a travelling wave similar to an initial travelling wave spectrum is searched to determine an arrival time of a first reflected travelling eave head of a fault, thereby completing fault location rapidly and accurately. Moreover, direct manual wave head determination is avoided, so that the arrival time of the wave head can be determined easily. The provided algorithm belongs to the relay protection field in the high-voltage line and has the advantage of improved accuracy of single-end fault location of the power transmission line.